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1.
Since surf zone hyperbenthos, although highly important in local food webs, has often been neglected and very little information is available, a survey of the Belgian sandy beaches was carried out from May 1996 until July 1997. Monthly samples were taken to give a complete record of hyperbenthic organisms occurring in the surf zone of Belgian sandy beaches and to evaluate the intensity by which this surf zone is used. In total 172 species were recorded. The number of species occurring in the surf zone is comparable to that of adjacent areas. As well as true hyperbenthic species, endobenthic and planktonic organisms were sampled. More than 75% of the average total sample composition consisted of mysids, mainly Mesopodopsis slabberi,Schistomysis spiritus and Schistomysis kervillei (holohyperbenthos). Apart from several resident species, active and passive seasonal migration towards the surf zone by a number of species is suggested. A large number of sporadic species adds to the composition of surf zone hyperbenthos. Within the merohyperbenthos, postlarval decapods and fish were the dominant organisms. During the year three recruitment peaks were observed. Average densities per month exceeded 1500 ind. 100 m−2. Yearly biomass averages ranged from 300 to over 3000 mg ADW 100 m−2. Densities of the common species are slightly higher in the surf zone than in other habitats, emphasising the importance of the area. Besides a possible nursery function, the surf zone may also be used as a transient area between different habitats. Finally, the influence of several abiotic factors on the hyperbenthic assemblages was evaluated. The main structuring variables determining the occurrence of most of the organisms are water temperature and hydrodynamic factors such as wave height and turbidity. The influence of wave height seems to be two-fold: several good swimmers such as mysids and some fish species are suggested to be able to actively avoid severe wave conditions, whereas other, more planktonic organisms, are passively transported towards the area if wave height increases.  相似文献   

2.
Sea-level rise is likely to cause significant changes in the morphodynamic state of beaches in the higher latitudes, resulting in steeper beaches with larger particle sizes. These physical changes have implications for beach invertebrate communities, which are determined largely by sediment particle size, and hence for ecosystem function. Previous studies have explored the relationships between invertebrate communities and environmental variables such as particle size, beach slope and exposure to wave action, and often these physical variables can be integrated in various indices of morphodynamic state. Most of these studies incorporated a full range of beach types that included wave-dominated surf beaches, where the wave action is harsh enough to enable reliable estimates of breaker height, a parameter included in several of the indices, and concluded that more dissipative beaches with gentler slopes and finer particle sizes often support a higher number of species and greater abundance than more reflective beaches. Whether these predictions remain valid for less wave-dominated beaches, where breaker height is more difficult to determine, is uncertain. In the present study, the abundance of meio- and macrofauna was quantified across a range of beaches in the UK, which are generally towards the lower energy end of the morphodynamic gradient, and their relationships with beach physical properties explored. No significant relationships were found between abundance and the standard morphodynamic indices, but significant relationships were found for both macro- and meiofaunal abundance when these indices were combined with an exposure index (derived from velocity, direction, duration and the effective fetch). All the relationships identified between abundance and combined morphodynamic indices indicated a higher abundance of both macro- and meiofauna on the more dissipative beaches. The reverse was however found for species richness. If predictions that accelerated sea-level rise will move beaches towards a more reflective morphodynamic state are correct, this could lead to declines in the abundance of meio- and macrofauna, with potential adverse consequences for ecosystem functioning.  相似文献   

3.
Variations in environmental factors can alter the species distribution pattern in intertidal rocky shores. The Persian Gulf (PG) and the Gulf of Oman (GO) vary substantially with respect to environmental and oceanographic conditions. The abundance and biodiversity of intertidal rocky gastropods in five locations across the northern PG and the GO were compared, and the environmental variables underlying the distribution pattern of these organisms were investigated. A total of 67 gastropod species were identified. The largest average density (294 ind./m2) and diversity (N = 43) for gastropods occurred in the Hotel Lipar station (LIP) located in Chabahar Bay in the GO. Clypeomorus bifasciata (107.43 ind./m2) followed by Cerithium caeruleum (94.67 ind./m2) were the most abundant species. Planaxis sulcatus and Siphonaria spp. occurred in all locations during both sampling occasions. Species richness and abundance of gastropods showed significant differences between LIP and remaining locations. A significant difference was found in assemblage structure across locations. In general, the species richness and density in the locations at GO were significantly larger than those locations in the PG, suggesting that the harsh environmental condition in the PG might be the forcing factor for this diminish. Distinct grouping was observed in both assemblage structure and species composition between locations in the PG and the GO. The spatial and temporal distribution patterns of gastropods assemblages were significantly correlated with variation in salinity and substrate rugosity.  相似文献   

4.
Habitat heterogeneity can influence biological communities by providing a diversity of areas that can be occupied by different species. Sandy beach surf zones are often considered homogenous environments; however, sand bars moved by currents and waves can produce trench‐like shapes or troughs that provide heterogeneity. The influence of habitat heterogeneity produced by sand movement is unclear despite the fact that surf zones are an important habitat for larval and juvenile fish and macrocrustaceans. To determine if, and how, the fish and macroinvertebrate communities present in trough and non‐trough or flat areas of Oregon surf zones differ, we compared species assemblages in both areas at three beaches adjacent to estuary mouths over 2 years. Troughs had different communities compared with flat areas, with higher total catch (mean ± SD = 123.2 ± 122.1 versus 43.6 ± 44.5 individuals × 100 m?2) and taxon richness (6.7 ± 2.7 versus 4.0 ± 2.3 taxa); these differences were potentially due to water movement, prey availability and sediment size. The fish and macroinvertebrate communities did not vary between years but there were significant differences among beaches, with the most distinct community present at the only beach adjacent to an estuary without a jetty at its mouth, which was possibly due to higher species movement between the surf zones and estuary. Fish and macrocrustacean surf zone communities varied spatially within and among beaches in relation to habitat heterogeneity provided by sand movement and, potentially, the influence of adjacent habitats.  相似文献   

5.
Sandy beach/surf‐zone ecosystems are unique environments that, despite the harsh and highly variable hydrodynamic conditions, present a diverse and heterogeneous fauna. However, the dynamics of these ecosystems are currently poorly understood. In this study we tested the hypothesis that surf‐zone assemblages vary with temporal factors such as time of day, tide and tidal height. To test this hypothesis, the surf‐zone community of Bastendorff, a Southern Oregon sandy beach was sampled during the summer of 2006. Samples were collected to (i) describe the smaller, benthic and larger swimming assemblages, (ii) determine whether assemblage compositions, densities, species richness and diversity vary with time of day, tide and tidal height, (iii) explore potential reasons for the variation by correlating environmental factors to the assemblages, and (iv) identify particular species that most strongly exhibit these variations. A hyperbenthic sledge, a sediment corer and a beach seine were used to collect the smaller swimming, benthic and larger swimming fauna, respectively. Sampling occurred during day and night, spring and neap tide, and high, mid and low tide. A total of 76,743 individuals belonging to 105 species were collected. Ninety‐one invertebrate (72,904 individuals), 15 invertebrates (2234 individuals), and 19 invertebrate and vertebrate species (1605 individuals) were collected with the sledge, corer and seine, respectively. Nine species of fish were caught, 98% of which were juveniles. The smaller and larger swimming assemblages varied most strongly with the time of day, suggesting certain species will actively move to the shallow surf‐zone at night. The three assemblages also varied with the tide, potentially due to the larger waves and higher abundance of detached macrophytes observed during spring tides when compared to neap tides, which could push individuals into the surf zone. The benthic assemblage most strongly varied with tidal height and sand grain size, confirming the presence of different faunal zones within Oregon sandy beaches. Finally, several variables of the swimming assemblages varied with temperature and salinity, suggesting that downwelling favorable conditions may have transported species close to shore. Bastendorff presents a complex and diverse surf‐zone community that appears to be influenced by diel species movements, environmental variables such as wave height and abundance of detached macrophytes, and regional oceanographic conditions.  相似文献   

6.
We aim to understand the relationships between physical conditions and characteristics of the immature-fish community in surf zones of sandy beaches. Therefore, we obtained fish samples between March 2007 and February 2008 and analyzed certain physical conditions in the surf zones of 21 sandy beaches on the coastline of the northwestern Kyushu Island, Japan. We collected a total of 83 species and 6458 immature individuals. In a BIO-ENV analysis, the highest correlation was observed between fish assemblage and S20 (i.e., the slope from the shoreline to the sites where the depth was 20 m) and current velocity (CV) values. Stepwise multiple linear regression analyses revealed that the number of species and individuals decrease with an increase in the S20 and CV values. These results show that species richness and the abundance of immature-fish increase under shelving and calm conditions. Thus, immature-fish assemblages are strongly influenced by the prevailing physical conditions. Moreover, in six of the 10 dominant species, a negative correlation was observed between CV and abundance. On the other hand, S20 was found to be the explanatory variable only in the case of the most dominant species, i.e., Gymnogobius breunigii. Furthermore, a positive correlation was observed between S1 (i.e., the slope from the shoreline to the sites where the depth was 1.0 m at the mean tidal level) and median particle size (i.e., MPS of the sediments) and the abundances of Sillago japonica and Favonigobius gymnauchen, respectively, and a negative correlation with salinity, in the case of Acanthogobius lactipes. We conclude that the characteristics of the fish community in surf zones on sandy beaches are determined by not only the shelving and calm conditions, which influence fish assemblages and abundances, but also the habitat diversity, which influences the diversity of fish species.  相似文献   

7.
Surf zones are highly dynamic, physically stressful parts of sandy beach ecosystems. The high wave energy of surf zones has in the past severely hampered ecological surveys of these systems. Here we used a novel technique to collect fauna from this environment along the Dutch coast. A large vehicle in the form a tripod that drives along the sandy seafloor and supports a sampling platform 11 m above the water line can collect both infaunal (grabs) samples and pull beam trawls for epibenthos. The distribution and diversity of macrofauna were studied at different depths in the surf zone along the Dutch coast. Species diversity and abundance increased with increasing depth of the water column. This increase was especially noticeable on the seaward side of the outer breaker bar. Within the surf zone, in the trough between the two breaker bars, there were spots of high diversity and abundance of macrobenthic infauna. Moreover, the area is also important for epibenthic and fish species, like the commercially important flatfish sole. Spatial patterns of species richness and abundance across an onshore-offshore gradient from the beach to seawards of the breakers suggest the presence of faunal zonation in this environment. The high abundance recorded in troughs was primarily caused by patches of juvenile Sand mason Lanice conchilega. The management implications of these results are that we suggest to protect the surf zone, including the trough between the two breaker bars, as a potential area of high diversity and abundance and to reconsider the objectives of the EU-Habitat Directive and the Water Framework Directive for the coastal area.  相似文献   

8.
2010年夏季雷州半岛沿岸海域浮游动物群落结构特征   总被引：4，自引：1，他引：3  
2010年7月对雷州半岛海岸带的浮游动物群落结构及相关环境因子进行了调查,共鉴定出浮游动物87种和34类浮游幼体,其中原生动物4种,占总种类数的4.6%;腔肠动物20种,占总种类数的23.0%;介形类1种,占总种类数的1.1%;枝角类2种,占总种类数的2.3%;桡足类37种,占总种类数的42.5%;十足类2种,占总种类数的2.3%;毛颚动物7种,占总种类数的8.0%;被囊动物6种,占总种类数的6.9%;浮游软体动物8种,占总种类数的9.2%。优势种有13种和3类浮游幼体,孔雀强额哲水蚤和小毛猛水蚤是该海域重要的优势种群,几乎在全海域均为优势种,桡足类幼体为全海域优势类群。半岛沿岸海域浮游动物种类数由近岸往远岸逐渐增多,浮游动物丰度分布则相反。浮游动物种类数由多到少的顺序为东北部、东南部、西北部和西南部、南部,丰度由大到小的顺序为西北部、西南部、东北部、东南部、南部,生物量由大到小的顺序为东北部、西南部、西北部、东南部、南部,浮游动物丰度和生物量的平面分布反映了人类对海岸带开发利用的活动概貌。多样性指数和均匀度平均值分别为2.96和0.57。相关分析表明:浮游动物丰度与水温、细菌总数、浮游动物生物量均呈极显著的正相关关系,与磷酸盐呈显著的负相关关系;浮游动物生物量与TOC、细菌总数、叶绿素a、浮游植物丰度均呈极显著的正相关关系,与pH呈显著的正相关关系,与盐度呈显著的负相关关系。  相似文献   

9.
Fish assemblages from two beaches, one in the inner and the other in the outer Sepetiba Bay (latitude: 22°54′–23°04′S; longitude: 43°34′–44°10′W), Southeast Brazil, were sampled by beach seine net, simultaneously, on both seasonal and diel scales, between August 1998 and June 1999. Sites were selected to encompass different environmental conditions which reflect the two bay zones, thus providing a comprehensive assessment of the factors influencing surf zone fish assemblages, and their spatial, seasonal and diel variations. A total of 55 fish species was recorded, mostly young-of-the-year. Anchoa tricolor, Micropogonias furnieri, Gerres aprion, Diapterus rhombeus, Harengula clupeola, Atherinella brasiliensis and Mugil liza were numerically dominant and contributed to 95.2% of the total fish catches. Strong differences in fish assemblages were observed between the two areas, with higher number of species in the outer bay. Increases in fish numbers occurred in winter, while the highest biomass occurred in winter and summer. Transparency, followed by salinity, was responsible for most of the spatial variability and played an important role in structuring fish assemblages. Overall, diel patterns did not reveal any significant trends; however, if we consider each season separately, an increase in fish numbers during the day with peak at sunset was observed in winter, and a higher biomass occurred at night in winter and summer. Species preferences for various combinations of environmental variables are responsible for shifts in the structure and overall abundance of assemblages and dictated some patterns. The sciaenid M. furnieri, the second most abundant species, occurred only in the inner zone, being more abundant in winter. The species of Engraulidae were more abundant in the outer zone in winter/spring during the day. The gerreids G. aprion and D. rhombeus occurred mainly in summer. Overall, temporal fluctuations act more at a specific level than at a structural one, and may be linked to some particular stages of the fish life cycle, but do not significantly influence the spatial organization.  相似文献   

10.
This study describes the distribution patterns of interstitial polychaetes along morphodynamic gradients on six exposed sandy beaches in Santa Catarina and Paraná (South Brazil). Three random transects were sampled at two points on each beach, one at the swash and another at the surf zone, in winter and summer conditions. Six sediment replicates were collected at each sampling point using a corer of 4.6 cm internal diameter that removed 10 cm into the sediment. Abundance and composition of interstitial polychaete were correlated to wave height, slope, grain size, CaCO3, chlorophyll a , omega indexes, temperature and relative tide range using a canonical correspondence analysis (CCA). A factorial ANOVA showed that taxa richness, mean density and Shannon's diversity were significantly higher at the reflective beaches, but average values differ significantly between transects and these differences change according to the beach zones on both sampling dates. PERMANOVA showed that polychaete associations differ among transects according to the beach zones. The composition of interstitial polychaete associations was significantly correlated to beach morphodynamics and features (P < 0.01). Polychaete associations of reflective beaches were more diverse than in other morphodynamic states. Intermediate beaches may also sustain diverse associations due to temporal variability of the morphodynamic patterns. Beaches presenting extreme dissipative morphodynamics and compacted sediments appear to be unfavourable for the occurrence of interstitial polychaetes.  相似文献   

11.
The size of bottom‐up subsidies, food and larvae, from the ocean has a profound impact on inter‐tidal communities and populations. Alongshore variations in subsidies are attributed to variation in coastal conditions, but also might be due to variations in surf‐zone hydrodynamics. We tested this hypothesis by comparing surf‐zone phytoplankton concentrations to surf‐zone hydrodynamics as indicated by the width of the surf zones. To minimize the potential effects of alongshore variation in phytoplankton abundance in the coastal ocean, we sampled closely spaced sites (median separation 1 km) over short periods (3 days). Surf‐zone concentrations of coastal phytoplankton taxa (e.g. Chaetoceros spp., Pseudo‐nitzschia spp. and dinoflagellates) varied with surf‐zone width; 65% to 94% of the variability in their concentration is explained by surf‐zone width. Where surf zones were narrow and more reflective, phytoplankton concentrations were one to several orders of magnitude lower than in wider, more dissipative surf zones. The most closely spaced stations were 30 m apart, but represented distinct habitats – a reflective and a more dissipative surf zone. Phytoplankton concentrations in the reflective surf zone were an order of magnitude or more lower than in the adjacent more dissipative surf zone. A reanalysis of a published study on phytoplankton subsidies found similar results. Alongshore variation in surf‐zone hydrodynamics appears to be an important driver of phytoplankton subsidies to the inter‐tidal zone.  相似文献   

12.
This study describes the macrofauna of the three beaches situated in central Gulf of Gabès (Tunisia): Ouderef, Gabès and Zarrat. The Gulf of Gabès has the largest tides in the Mediterranean and the beaches showed a wide intertidal zone. The beaches were sampled once during the spring low tides of June 2005. A transect was extended at each beach, from above the drift line to below the swash line at five sampled levels; at each level six 0.05 m2 replicates were taken to a depth of 30 cm and sieved through a 1-mm mesh, and the organisms collected and preserved. The three beaches showed a different physical environment. Sediment type was medium sand at the steeper Ouderef beach, fine sands at Gàbes beach, and very fine sands at the flatter Zarrat beach. The total number of species collected was 31: 12 crustaceans, 10 polychaetes, four molluscs and five insects. The supralittoral and mediolittoral zones were very different. The supralittoral zone was dominated by Talitrus saltator and insects. The most abundant mediolittoral species were the amphipod crustacean Bathyporeia guilliamsoniana at Ouderef beach (23069 ind.m−1), the surf clam Donax trunculus at Gabès beach (60711 ind.m−1) and the spionid polychaete Scolelepis mesnili at Zarrat beach (18345.6 ind.m−1).  相似文献   

13.
The analysis of 79 hauls performed by commercial bottom trawlers from 50 to 800 m depth in the Balearic Sea (north-western Mediterranean) from June 1995 to September 1996 yielded a total of 30 cephalopod species belonging to 12 families. Cluster analysis of these data gave as a result two main groups 50–200 m and 200–800 m each subdivided into two other groups (50–100 vs. 100–200 m and 200–600 vs. 600–800 m). These results suggested the existence of two assemblages that could be associated to the continental shelf (50–100 m) and the upper slope (600–800 m) separated by a wide transitional zone (100–600 m) representing a region of overlapping shelf and slope faunas (ecotone). The faunistic bathymetric gradient showed a continuous substitution of species with depth rather than discrete assemblages separated by distinct boundaries. The more coastal species such as Eledone moschata, Loligo vulgarisSepia officinalis and Octopus vulgaris were found on the continental shelf; on the transitional zone, apart from species characteristic of this zone (Illex coindetii, Sepietta oweniana, Rossia macrosoma, Scaeurgus unicirrhus and Pteroctopus tetracirrhus), we also observed species from both the continental shelf and slope. The upper slope was characterized by typical species of deeper waters, such asBathypolypus sponsalis , Histioteuthis reversa, H. bonnellii, Ancistroteuthis lichtensteinii andOnychoteuthis banksii . The octopod O. vulgaris was the dominant species on the continental shelf and upper transitional zone, being substituted by T. sagittatus on the lower transitional zone and upper slope. Mean biomass decreased abruptly from the continental shelf to the transitional zone and from there to the upper slope. Mean species richness and species diversity were higher in the transitional zone than in the continental shelf and upper slope. Finally, some biological aspects of the more abundant deep-sea cephalopod species are studied: Bathypolypus sponsalis, Octopus salutii,Pteroctopus tetracirrhus , Histioteuthis reversa and H. bonnellii.  相似文献   

14.
Ten exposed sandy sites covering a range from reflective to dissipative beaches were sampled in south-central Chile to evaluate: (1) spatial changes in species richness, abundance and biomass of the intertidal macroinfauna in response to changes in mean grain size, beach face slope and beach type, and (2) spatial changes in abundance, biomass and body sizes of the most abundant species in response to changes in the physical factors. The number of species, abundance and biomass per beach in general decreased with increasing particle size and beach face slope (steeper beaches) and increased from reflective to dissipative conditions. The best fit for number of species was with Dean's parameter, a measure of beach type, whereas for abundance and biomass the best fits were found with particle size. The isopod Excirolana braziliensis and the anomuran Emerita analoga increased in abundance and biomass towards dissipative conditions, whereas Excirolana hirsuticauda showed the opposite trend in biomass and was significantly larger in beaches with steeper profiles. It is concluded that responses to changes in beach type are more pronounced at community level than within species populations.  相似文献   

15.
Use of coastal armoring is expected to escalate in response to the combination of expanding human populations, beach erosion, and sea level rise along the coasts. To provide a conceptual framework, we developed hypotheses concerning the ecological effects of beach habitat loss associated with coastal armoring. As beaches narrow in response to armoring, dry upper intertidal zones should be lost disproportionately, reducing the habitat types available and the diversity and abundance of macroinvertebrates. Predators, such as shorebirds, could respond to a combination of (i) habitat loss; (ii) decreased accessibility at high tides; and (iii) reduced prey availability on armored beaches. To examine those predictions, zone widths and the distribution and abundance of macroinvertebrates and birds were compared on paired armored and unarmored segments of narrow bluff-backed beaches in southern California. Our results supported the predictions and revealed some unexpected effects of armoring on birds. Dry upper beach zones were lacking and mid-beach zones were narrower (>2 times) year-round on armored segments compared to adjacent unarmored segments. The abundance, biomass and size of upper intertidal macroinvertebrates were also significantly lower on armored segments. Shorebirds, most of which were foraging, responded predictably with significantly lower species richness (two times) and abundance (>3 times) on armored segments. Gulls and other birds (including seabirds), which use beaches primarily for roosting, were also significantly lower in abundance (>4 times and >7 times respectively) on armored segments, an important unexpected result. Given the accelerating pressures on sandy beaches from coastal development, erosion and rising sea levels, our results indicate that further investigation of ecological responses to coastal armoring is needed for the management and conservation of these ecosystems.  相似文献   

16.
The across shore variability and trophodynamics of meiofauna were studied in a microtidal beach of the Thyrrenian Sea (NW Mediterranean). Two sites were sampled at Collelungo beach (Maremma Park, Italy) subjected to different regimes of sediment erosion and deposition. At each site, four levels were sampled in November 2002 and May 2003 along a transect from the supralittoral zone to the surf zone. Sediment cores were taken down to a depth of 10 cm and meiofaunal abundance and community structure were analyzed and related to the principal trophic resources (quantity and quality of organic matter, chlorophyll a, bacteria density and biomass).Meiofaunal abundance ranged between 14 ind. 10 cm−2 and 716 ind. 10 cm−2 in the top 0–10 cm of sediment. Abundance was lower in the surface (0–2 cm) than in the deeper (5–10 cm) sediment layers but no significant differences were found between the two sites.Multivariate BIOENV analysis showed that dryness, grain size (related to physical processes) and bacterial biomass, were the main variables explaining meiofauna distribution in these beaches. Meiofaunal densities and number of taxa were always higher at the swash level, while lower abundances were observed at the dry sampling level (+5 m). This across shore trend was also observed for the quality of the organic matter (PRT/CHO) and bacterial densities. Nematode assemblage structure at the swash sampling level showed a dominance of non-selective deposit feeders (1B), with Xyalidae as the dominant family (56%), followed by Thoracostomopsidae (14%) and Selachnematidae (12%).According to the findings, physical and biological variables at the swash level create optimal living conditions for the meiobenthos, making the swash a key area within the beach ecosystem, with potential implications within basic and applied ecological studies.  相似文献   

17.
海滩近岸带中尺度地形动力过程是海岸海洋科学研究的重要研究内容之一.近20年来该领域发展较快,取得了一些重要的成果.对近岸带中尺度地形动力过程的碎波带地形与沙坝、冲流带地形与滩角、海滩风暴响应、观测技术手段等主要领域的进展进行了总结和评述,并对我国海滩研究提出要从加强观测手段和制定长期观测计划两方面来加强的建议.  相似文献   

18.
山东长岛潮间带大型底栖动物生态特征研究   总被引：4，自引：1，他引：3  
2015年11月(秋季)、2016年2月(冬季)、2016年6月(春季)、2016年9月(夏季)大潮期间对山东长岛列岛中南长山岛和北长山岛的3个不同底质类型的潮间带采样点进行了系统的大型底栖动物调查,研究了其数量特征和季节变化,包括群落种类组成、密度和生物量、优势种、物种多样性等,结果表明:本次调查共鉴定出大型底栖动物隶属7个门,共81种。其中环节动物门多毛类动物25种,软体动物门25种,节肢动物门22种,棘皮动物门6种,其他类群共3种(包括纽虫、腔肠动物和鱼类各1种)。潮间带大型底栖动物平均密度为118.97 ind./m~2,软体动物和甲壳动物占据了研究区域底栖群落的密度主要成分,两者分别占比为39.58%和36.68%。各采样点平均密度为北长山岛(BCS)(141.17 ind./m~2)避险角(NCS1)(122.33ind./m~2)明珠广场东(NCS2)(93.42ind./m~2);各采样点平均生物量为128.03g/m~2,软体动物和甲壳动物占据了研究区域底栖群落的生物量主要成分,两者分别占比为58.56%和35.32%。平均生物量北长山岛(BCS)(234.95g/m~2)避险角(NCS1)(99.99g/m~2)明珠广场东(NCS2)(49.13g/m~2)。从季节来看,各站点的物种数、平均密度和生物量季节变化的规律性不明显,总体为秋、春季较多,夏、冬季较少。3个站点物种多样性指数(H′)、丰富度指数(D)和均匀度指数(J′)平均值分别为2.30、1.99和0.79,各潮区中,均为中潮带低潮带高潮带,各季节变化不明显。优势种受底质类型和季节变化的影响明显,没有在各站点和季节均为优势种的种类,主要的优势种有平背蜞(Gaetice depressus)、绒螯近方蟹(Hemigrapsus penicillatus)、短滨螺(Littorina brevicula)等。与以往历史资料相比,长岛潮间带生物出现了一定变化,种类和数量减少,与烟台近岸潮间带大型底栖动物种类组成差别很大。  相似文献   

19.
Larval fishes were collected from the surf zone of Horn Island, Mississippi between March 1978 and April 1979. A standardized total of 39 435 larvae were taken from 222 collections in the inner and outer surf zone regions, representing fish in 69 taxa. Overall, considerably more larvae were collected in the outer surf zone (78·3%) than in the inner surf zone (21·7%). Engraulids, Chloroscombrus chrysurus and Symphurus spp. were the most abundant larvae taken from the outer surf zone while engraulids, Leiostomus xanthurus, Brevoortia patronus and Trinectes maculatus were the numerically dominant larvae in the inner surf zone. Seasonal peaks in abundance occurred at the outer surf zone stations during May and June and at the inner surf zone stations during December. Larval densities were significantly greater in night collections than in day collections.The occurrence of early larvae, late larvae and juveniles suggests that the surf zone habitat is important to several species of coastal marine fishes. Menticirrhus littoralis, Harengula jaguana and Trachinotus carolinus appear to most readily utilize the surf zone as a nursery area.  相似文献   

20.
Meiobenthic data from two microtidal sandy beaches of the eastern Mediterranean (Crete, Greece) were used to investigate patterns of both alpha and beta diversity in space and time. Copepod assemblages and environmental variables related to sediment characteristics, morphodynamics and food were studied over a year at four distinct habitats at each beach; the retention, resurgence and saturation zones of Salvat's intertidal scheme (midlittoral zone), and the surf zone of the sublittoral. Αlpha diversity analysis indicated similar species richness at both beaches when the whole 13-month data set was considered but was higher at the sheltered site when each sampling period was examined separately. Both beaches supported higher diversity in the sublittoral zone. Species richness increased seawards at the midlittoral zone of the sheltered site whereas, no pattern was evident at the exposed site, where the intense hydrodynamic conditions homogenized the sediments. Beta diversity increased markedly towards the sublittoral, indicating greater differences in alpha diversity between the sublittoral and the midlittoral zone. Species turnover was more variable at the exposed beach and at the most landward stations, where environmental conditions change often between extremes. A proportion of the variation in alpha diversity was explained by food availability at both beaches and additionally by grain size at the sheltered site. However, no environmental variable explained beta diversity patterns. Although the results of our study support the hypothesis of Multicausal Environmental Severity proposed for sandy beach macrofauna, we believe the classic Intermediate Disturbance Hypothesis is a more appropriate framework for the meiofauna communities of the studied sites.  相似文献   

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